* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body, html {
      height: 100%;
      display: flex;
      justify-content: center;
      align-items: center;
      background-color: #6c4949;
    }
    #clock {
      width: 400px;
      height: 400px;
      background-color: #008c8c;
      font-size: 48px;
      font-family: 'Courier New', Courier, monospace;
      display: flex;
      justify-content: center;
      align-items: center;
      /* 字体加粗 */
      font-weight: bold;
      /* 倒影效果 */
      -webkit-box-reflect: below 0 linear-gradient(transparent, rgba(0, 0, 0, 0.2));
    }